The objective of this K08 Award for Thomas Barrett, M.D., Ph.D., is to prepare the candidate to be an independent investigator in functional neurobiology and molecular genetics relevant to psychiatric disorders. He developed a strong foundation in molecular and cellular biology doing Ph.D. and fellowship work, then, six years ago began retraining to do basic psychiatric research. Career Development Plan: The candidate's goal is to prepare himself to be an academic researcher investigating the biological basis of bipolar disorder (BPD). His training objectives are designed to develop a strong foundation in analysis of gene function and the effect of variants, in molecular genetics, and in statistical genetics. Specific objectives are: 1. clinical study design, diagnosis, and ascertainment; 2. high throughput sequencing and genotyping, and bioinformatics; 3. experimental design and statistical analysis for positional cloning studies, especially linkage analysis and association studies; 4. the development of molecular and cellular assays to test for functional effects of candidate mutations, particularly promoter and enhancer analysis; 5. the analysis of candidate mutations that effect cell signaling systems. Research Plan: Genome-wide linkage scans suggest a susceptibility gene for BPD lies at or in the vicinity of the gene G protein receptor kinase-3 (GRK3) on chromosome 22. GRK3 desensitizes many G proteincoupled receptors. Preliminary data indicate that a variant in the promoter region of GRK3 is associated with BPD. Transmission disequilibrium analysis in two triad sets gave a combined p-value = 0.0019. The hypothesis that altered regulation of GRK3 results in hypersensitivity to neurotransmitter signaling and susceptibility to BPD will be tested. The candidate will reanalyze available data to substantiate linkage to the GRK3 region of ch22. Additional haplotypes in the implicated region will be identified and tested for association with disease. A cell culture expression vector system will be established to test putative regulatory variants for functional effect. Functional studies will be done to assess GRK3 expression, including allele-specific expression, in lymphoblastoid cell lines from subjects with BPD. By these means the candidate proposes to test if GRK3, or another gene if so identified, is a susceptibility gene for bipolar disorder. [unreadable] [unreadable]